Abstract P147: Hemoglobin A1c Cut Points to Define Various Glucose Intolerance Groups in a South Asian Population
Objective: American Diabetes Association (ADA) has proposed a hemoglobin A1c cut point of 6.5% as a diagnostic test for diabetes (DM). It is important to know whether this cut point applies to populations worldwide. Here we determine the A1c cut points for various levels of glycemia in South Asian population, a ethnic group with high susceptibility to type-2 DM.
Methodology: We conducted a cross-sectional analysis in 6965 South Indians without history of DM. All had fasting plasma glucose (FPG) and 2-hour post-prandial plasma glucose (PPG) measurements after a 75-g glucose load and were classified to have Impaired Fasting Glucose (IFG; FPG ≥100 & ≤125 & PPG ≤139), Impaired Glucose Tolerance (IGT; FPG ≤99 & PPG ≥140 & ≤199), DM (FPG ≥126 or PPG ≥200) and normal glucose tolerance (NGT; FPG ≤99 & PPG ≤139) according to ADA criteria. A1c was measured using BIORAD D-10 A1c analyzer. Based on receiver operating characteristic curves, optimum sensitivity and specificity were derived for defining A1c cut points for DM, IFG, and IGT & NGT.
Results: Mean ± SD values of A1c among subjects with NGT, IFG, IGT, and DM were 5.62 ± 0.46, 5.94 ± 0.53, 5.93 ± 0.53 & 7.71 ± 1.50, respectively (p-trend <0.01). Distribution of A1c levels in these various categories is shown in the figure. To identify DM based on PPG, the A1c cut point was 6.3% [area under the curve (AUC) = 0.943; 89.0% sensitivity & 90.4% specificity] and based on FPG the A1c cut point was 6.6% [AUC = 0.983; sensitivity 95.1%, & specificity 93.8%]. For IGT, the A1c cut point was 5.8 [AUC = 0.580; 53.0% sensitivity & 58.9% specificity] and for IFG A1c cut point was 5.7 [AUC = 0.593; 61.6% sensitivity & 52.6% specificity].
Conclusion: In South Indian population, DM can be defined by A1c cut point 6.3% & 6.6% based on PPG & FPG levels, respectively. Whereas A1c cut point was 5.7% and 5.8% for IFG & IGT, respectively with <65% sensitivity and specificity. Further studies in non-western populations are needed before A1c can be universally recommended as a diagnostic test for diabetes and high-risk states (IGT and/or IFG).
Author Disclosures: M. Thanikachalam: None. V. Harivanzan: None. V. Nambi: None. S. Thanikachalam: None.
- © 2015 by American Heart Association, Inc.